Gene study supports single main migration across Bering Strait

Nov 26, 2007

The U-M study, which analyzed genetic data from 29 Native American populations, suggests a Siberian origin is much more likely than a South Asian or Polynesian origin. Credit: University of Michigan

Did a relatively small number of people from Siberia who trekked across a Bering Strait land bridge some 12,000 years ago give rise to the native peoples of North and South America?

Or did the ancestors of today’s native peoples come from other parts of Asia or Polynesia, arriving multiple times at several places on the two continents, by sea as well as by land, in successive migrations that began as early as 30,000 years ago?

The questions – featured on magazine covers and TV specials – have agitated anthropologists, archaeologists and others for decades.

University of Michigan scientists, working with an international team of geneticists and anthropologists, have produced new genetic evidence that’s likely to hearten proponents of the land bridge theory. The study, published online in PLoS Genetics, is one of the most comprehensive analyses so far among efforts to use genetic data to shed light on the topic.

The researchers examined genetic variation at 678 key locations or markers in the DNA of present-day members of 29 Native American populations across North, Central and South America. They also analyzed data from two Siberian groups. The analysis shows:

-- genetic diversity, as well as genetic similarity to the Siberian groups, decreases the farther a native population is from the Bering Strait – adding to existing archaeological and genetic evidence that the ancestors of native North and South Americans came by the northwest route.

-- a unique genetic variant is widespread in Native Americans across both American continents – suggesting that the first humans in the Americas came in a single migration or multiple waves from a single source, not in waves of migrations from different sources. The variant, which is not part of a gene and has no biological function, has not been found in genetic studies of people elsewhere in the world except eastern Siberia.

The researchers say the variant likely occurred shortly prior to migration to the Americas, or immediately afterwards.

“We have reasonably clear genetic evidence that the most likely candidate for the source of Native American populations is somewhere in east Asia,” says Noah A. Rosenberg, Ph.D., assistant professor of human genetics and assistant research professor of bioinformatics at the Center for Computational Medicine and Biology at the U-M Medical School and assistant research professor at the U-M Life Sciences Institute.

“If there were a large number of migrations, and most of the source groups didn’t have the variant, then we would not see the widespread presence of the mutation in the Americas,” he says.

Rosenberg has previously studied the same set of 678 genetic markers used in the new study in 50 populations around the world, to learn which populations are genetically similar and what migration patterns might explain the similarities. For North and South America, the current research breaks new ground by looking at a large number of native populations using a large number of markers.

The pattern the research uncovered – that as the founding populations moved south from the Bering Strait, genetic diversity declined – is what one would expect when migration is relatively recent, says Mattias Jakobsson, Ph.D., co-first author of the paper and a post-doctoral fellow in human genetics at the U-M Medical School and the U-M Center for Computational Medicine and Biology. There has not been time yet for mutations that typically occur over longer periods to diversify the gene pool.

In addition, the study’s findings hint at supporting evidence for scholars who believe early inhabitants followed the coasts to spread south into South America, rather than moving in waves across the interior.

“Assuming a migration route along the coast provides a slightly better fit with the pattern we see in genetic diversity,” Rosenberg says.

Relevant PhysicsForums posts

Related Stories

By comparing the genes of current-day North and South Americans with African and European populations, an Oxford University study has found the genetic fingerprints of the slave trade and colonisation that ...

African cattle infected with a lethal parasite that kills one million cows per year are less likely to die when co-infected with the parasite's milder cousin, according to a new study published today in Science Advances. The fi ...

Many people in the UK feel a strong sense of regional identity, and it now appears that there may be a scientific basis to this feeling, according to a landmark new study into the genetic makeup of the British ...

A ground-breaking Texas A&M AgriLife Research-led study on corn has identified useful gene variations for yield increases, drought tolerance and aflatoxin resistance that could make a real difference to Texas ...

The DNA you inherit from your parents contributes to the physical make-up of your body—whether you have blue eyes or brown, black hair or red, or are male or female. Your DNA can also influence whether ...

Dairy and other livestock farmers in the northern U.S. have three new alfalfa options this growing season – all pioneered by Cornell researchers as a way to combat devastating pests, increase yields and ...

Recommended for you

Spring is here and ectotherms, or animals dependent on external sources to raise their body temperature, are becoming more active. Recent studies have shown that as the average global temperature increases, ...

The intraterrestrials, they might be called. Strange creatures live in the deep sea, but few are odder than the viruses that inhabit deep ocean methane seeps and prey on single-celled microorganisms called ...

Until now electric fences and trenches have proved to be the most effective way of protecting farms and villages from night time raids by hungry elephants. But researchers think they may have come up with ...

Researchers at the Mechanobiology Institute, National University of Singapore, have made significant advances in our understanding of cellular biology; providing evidence that the inherent 'handedness' of ...

(Phys.org)—In the complex, somewhat rarified world of interactions between various flavors of RNA, one elusive goal is to understand the precise regulatory relationships between competing endogenous RNA ...

User comments : 2

Quote "The variant. . . has not been found in genetic studies of people elsewhere in the world except eastern Siberia. The researchers say the variant likely occurred shortly prior to migration to the Americas, or immediately afterwards."
If they found the variant in Siberia why would they possibly think that the variant could have occurred after the migration?

That puzzled me as well, but the preponderance of evidence in this large-scale study, verifies what was the main theory when I was in college 30 years ago. I have been keeping abreast of newer developments ever since. It would be nice to get clarification on when this trait ocurred.

Please sign in to add a comment.
Registration is free, and takes less than a minute.
Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.